Fuel supply system for motorcycle

ABSTRACT

The motorcycle includes a power unit having a crankcase of an internal combustion engine, a throttle body mounted to the power unit, a fuel injection system mounted on the throttle body, a fuel tank, the fuel pump unit by which a fuel in the fuel tank is supplied to the fuel injection system, and the fuel filter device. The fuel supply system for the motorcycle includes the fuel filter device disposed so as to overlap with the throttle body when viewed in the vehicle width direction, an upper portion of an outer case of the fuel filter device is supported by an engine hanger boss for fixing the power unit to a body frame of the motorcycle, and a lower portion of the outer case is supported by the crankcase.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 USC 119 to JapanesePatent Application No. 2009-224100 filed on Sep. 29, 2009 the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel supply system for a motorcycle.More particularly to a fuel supply system which has a space-savingdesign in regard to the installation space thereof and in which a fuelfilter device is firmly supported.

2. Description of Background Art

A fuel supply system for a motorcycle wherein a fuel filter device isdisposed on the downstream side of a fuel pump unit is shown in JapanesePatent Laid-open No. 2008-248753 (FIGS. 1 to 3, 5 and 6). The fuelsupply system shown in Japanese Patent Laid-open No. 2005-096504 (FIGS.1 and 2) has a configuration in which while the fuel pump unit isprovided inside a fuel tank, the fuel filter device is disposed on therear side of a throttle body and on the upper side of a crankcase, andis mounted through a bracket to a center frame extending vertically onthe rear side of a power unit.

On the other hand, a system in which, due to a restriction imposed by afuel tank or the like, a fuel pump unit is disposed on the upper side ofan output shaft in a crankcase of a power unit and on the front side ofa rear cushion is shown in Japanese Patent Laid-open No. 2005-096504.

In a fuel supply system for a motorcycle having a fuel filter deviceprovided on the downstream side of a fuel pump unit as shown in JapanesePatent Laid-open No. 2008-248753, a further space saving in regard oflayout space while achieving a further firm supporting of the fuelfilter device has been requested.

More particularly, in the case of a motorcycle using a gasoline-ethanolmix fuel as described in Japanese Patent Laid-open No. 2008-248753, itis highly necessary to provide a fuel filter device on the downstreamside of the fuel pump unit for the purpose of removing the dust presentin ethanol, and there has been a demand for firm supporting of the fuelfilter device outside a fuel tank.

In that case, also, there has been a demand for a fuel supply systemhaving a space-saving configuration in which a fuel pump unit can bedisposed outside the fuel tank, like in Japanese Patent Laid-open No.2005-096504.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of an embodiment of the present invention to provide afuel supply system for a motorcycle having a space-saving design inwhich a fuel filter device provided on the downstream side of a fuelpump unit can be firmly supported.

In order to attain the above object, according to an embodiment of thepresent invention, a fuel supply system for a motorcycle including apower unit having a crankcase of an internal combustion engine, athrottle body mounted to the power unit, a fuel injection system mountedon the throttle body, a fuel tank, a fuel pump unit by which a fuel inthe fuel tank is supplied to the fuel injection system, and a fuelfilter device, wherein the fuel filter device is disposed so as tooverlap with the throttle body as viewed in a vehicle width direction,and an upper portion of an outer case of the fuel filter device issupported by an engine hanger boss for fixing the power unit to a bodyframe of the motorcycle, whereas a lower portion of the outer case issupported by the crankcase.

According to an embodiment of the present invention, the outer caseincludes a support part side case provided on an inner side in thevehicle width direction in a mounted state, and a cover part provided onan outer side in the vehicle width direction and covering the supportpart side case; the support part side case is supported by the enginehanger boss and the crankcase; and the cover part is fixed to thesupport part side case in the condition in which a claw portion providedon one end side of the cover part is inserted into the support part sidecase and the other end side of the cover part is fastened to the supportpart side case by a fastening bolt.

According to an embodiment of the present invention, a part of a fuelpipe connectingly extending from the fuel filter device to the fuelinjection system is set winding around the outer case of the fuel filterdevice and is supported on the outer case, by a pipe support partprovided at the outer case, in such a manner so as to be adjacent to ahead portion of the fastening volt in a bolt axis direction.

According to an embodiment of the present invention, the fuel pump unitis located at a position below the fuel filter device, and the fuel pumpunit is supported by a fuel pump mounting stay mounted to a bracket forsupporting a lower portion of the fuel filter device.

According to an embodiment of the present invention, the internalcombustion engine has a crankshaft oriented in the vehicle widthdirection, the fuel filter device and the fuel pump unit are cylindricalin shape, and they are disposed so that their cylinder axes are orientedsubstantially in parallel to a cylinder axis of the internal combustionengine as viewed in the vehicle width direction.

According to an embodiment of the present invention, the motorcycle hasa rear shock absorber provided in a vertically oriented state, and thefuel pump unit is disposed on the rear side of the crankcase and on thefront side of the rear shock absorber.

According to an embodiment of the present invention, the motorcycle hasa swing arm supported by the rear cushion and rotatably supporting arear wheel, and the fuel pump unit is disposed at a position on avehicle inner side in the vehicle width direction relative to the swingarm, the position being such that the fuel pump unit overlaps with theswing arm when viewed in the vehicle width direction.

According to an embodiment of the present invention, the fuel pump unitis cylindrical in shape, and is disposed adjacently to the rear shockabsorber, with its cylinder axis oriented in a vertical directionsubstantially parallel to the rear cushion.

According to an embodiment of the present invention, the fuel filterdevice is disposed in a space on a lateral side of the throttle body ina space-saving manner and is supported at an upper portion and a lowerportion of the outer case thereof. Therefore, the fuel filter device issupported firmly.

According to an embodiment of the present invention, firm supporting ofthe fuel filter device is securely realized because the support partside case on the inner side in the vehicle width direction is supportedby the engine hanger boss and the crankcase. In addition, since thecover part is fixed to the support part side case by the claw portionand the fastening bolt on the outer side in the vehicle width direction,the cover part can be easily mounted and dismounted, so that maintenanceand replacement works for a fuel filter element and the like arefacilitated.

According to an embodiment of the present invention, the length of thefuel pipe from the fuel filter device to the fuel injection system issecured and optimization of the pipe length is contrived.Simultaneously, the fuel pipe is set along the fuel filter device,whereby the fuel pipe is laid in a space-saving manner.

Furthermore, since the fuel pipe set winding around the outer case issupported by a pipe support part in such a manner so as to be adjacentto a head portion of the fastening bolt in a bolt axis direction, thefastening bolt is prevented from slipping off even when loosened.

According to an embodiment of the present invention, a fuel pumpmounting stay for supporting the fuel pump unit can be made smaller insize, and the fuel pump unit can be supported in a space-saving manner.

According to an embodiment of the present invention, the power unit, thefuel filter device and the fuel pump unit can be laid out in a compactform without leaving a dead space.

According to an embodiment of the present invention, the fuel pump unitcan be laid out efficiently.

According to an embodiment of the present invention, the fuel pump unitis likely to be protected by the swing arm.

According to an embodiment of the present invention, the space on thefront side of the rear shock absorber can be utilized effectively andthe fuel pump unit can be disposed in a compact manner.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a side view showing a major part of a motorcycle having a fuelsupply system for motorcycle according to an embodiment of the presentinvention;

FIG. 2 is an enlarged side view of the vicinity of a power unit shown inthe side view of FIG. 1;

FIG. 3 is a perspective view from a skew upper side, taken along arrowIII of FIG. 2 to show the layout of apparatuses in the vicinity of thepower unit;

FIG. 4 is a perspective view from a skew lower side, taken along arrowIV of FIG. 2 to show a rear portion of the power unit and a fuel pump;

FIG. 5 is an apparatus layout illustration taken along arrow V of FIG.3, showing a left side surface of the vicinity of the power unit;

FIG. 6 is an apparatus layout illustration taken along arrows VI of FIG.5, showing a condition where the power unit has been removed;

FIG. 7 is an apparatus layout illustration taken along arrow VII of FIG.5, showing a condition where the power unit has been removed;

FIG. 8 is a perspective view of a fuel filter device, taken along arrowVIII of FIG. 7;

FIG. 9 is a perspective view of the fuel filter device, taken alongarrow IX of FIG. 8 to show an outside portion where a base part forseating a pressure regulator thereon is formed;

FIG. 10( a) is a side view of a fuel tank according to this embodiment,and FIG. 10( b) is a general bottom view of the fuel tank, taken alongarrow Xb of FIG. 10( a); and

FIG. 11( a) is a sectional side view of the vicinity of a reinforcingplate, or area XI of FIG. 10, and FIG. 11( b) is a partial bottom viewof the fuel tank in the vicinity of the reinforcing plate, taken alongarrow XIb of FIG. 11( a). FIG. 11( a) is a sectional side view takenalong arrows XIa of FIG. 11( b).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A fuel supply system for motorcycle according to an embodiment of thepresent invention will now be described below, based on FIGS. 1 to 11(b).

In each of the drawings, apparatuses and members are partly cut out, andapparatuses and members other than major ones in the present inventionare omitted together with fenders, covers, etc.

Small arrows added to apparatuses or pipes in each drawing showschematically the flow direction of a fuel.

In addition, the directions such as front, rear, left, right, up, down,etc. in the descriptions herein are according to the direction of avehicle (motorcycle) in the condition where the motorcycle is providedwith the fuel supply system for a motorcycle according to thisembodiment.

In the drawings, arrow FR indicates the front side of the vehicle, LHindicates the left-hand side of the vehicle, RII indicates theright-hand side of the vehicle, and UP indicates the upper side of thevehicle.

The phrase “a vertical direction” herein is not limited to the strictlyvertical direction but widely includes those directions in which thevertical component is greater than the horizontal component.

FIG. 1 shows a major part of a left side view of a motorcycle 1according to an embodiment of the present invention.

A body frame 2 of the motorcycle 1 includes: a head pipe 3; a singlemain frame 4 extending rearwardly downward from the head pipe 3 and isoriented along the front-rear direction of the vehicle; a center frame 5extending downward from the rear end of the main frame 4; a down frame 6extending downward from the head pipe 3; a pair of left and right seatstays 7 extending rearwardly upward from the main frame 4; a pair ofleft and right mid frames 8 connecting a portion near the lower end ofthe center frame 5 to the seat stays 7; and a reinforcing frame 9interconnecting the down frame 6 and the main frame 4.

The center frame 5 is branched on the lower side relative to a jointportion for jointing to the main frame, into a pair of left center frame5 a and a right center frame 5 b. The down frame 6 extends downward, andis branched on the lower side of a mounting portion of a front bracket25 for supporting a power unit 30, into a pair of left down frame 6 aand a right down frame 6 b. The left down frame 6 a and the right downframe 6 b are bent to the rear side, and extend substantiallyhorizontally, to be connected respectively to the lower ends of the leftcenter frame 5 a and the right center frame 5 b.

In the following description, when it is unnecessary to separately pointout a left member and a right member (of a left-right pair of members),the left and right members are collectively referred to simply as “thecenter frame 5,” and “the down frame 6.”

A front fork 11 for rotatably supporting the front wheel 10 is steerablysupported by a steering stem (not shown) provided in the head pipe 2, atop bridge 12 and a bottom bridge 13. A steering handle 14 is connectedto the top bridge 12, and a meter unit 15 is mounted on the front sideof the top bridge 12. A head light 17 covered by a cowl 16 is attachedto the top bridge 12 and the bottom bridge 13. A seat 18 is mounted ontothe seat stays 7.

At a rear portion of the center frame 5, the front end side of a swingarm 20 for rotatably supporting a rear wheel 19 is pivotally supportedon pivot brackets 21 provided on the center frame 5, by a pivot shaft 22extending in the vehicle width direction.

In addition, between a seat stay bracket 7 a provided at a mountingportion of the seat stay 7 onto the main frame 4 and the swing arm 20, arear shock absorber 23 is provided in a vertical orientation on thefront side of the rear wheel 19, and the swing arm 20 is supported bythe rear shock absorber 23 so as to be vertically swingable about thepivot shaft 22.

The power unit 30 is comprised of an internal combustion engine 31constituting a front portion of the power unit 30, and a transmission(not shown) provided inside a crankcase 32 to constitute a rear portionof the power unit 30. The internal combustion engine 31 is asingle-cylinder 4-stroke-cycle internal combustion engine, and itscylinder section 33 is provided to project upward from a front portionof the crankcase 32 in the state of being slightly slanted forward. Inother words, the crankcase 32 constitutes a so-called power unit case.

The power unit 30 is supported by being suspended from an engine hangerboss 24 provided on the reinforcing frame 9, and its front and rearportions are supported by a front bracket 25 provided on the down frame6 and a rear bracket 26 provided on the center frame 5, whereby thepower unit 30 is mounted on the motorcycle 1, with the crankshaft 34 ofthe internal combustion engine 31 oriented in the vehicle widthdirection.

Power of the power unit 30 is transmitted from the crankshaft 34 througha clutch, a speed reducing mechanism and the like of the transmission(not shown), to be taken out through an output shaft 35 projecting outfrom a left side surface of a rear portion of the crankcase 32. Thepower is transmitted to the rear wheel 19 through a rear wheel drivesprocket 36 attached to the output shaft 35, a rear wheel drive chain37, and a rear wheel driven sprocket 38 attached to the rear wheel 19.

The layout and configuration of the power unit and the fuel supplysystem in the motorcycle according to this embodiment will be describedreferring to FIG. 2, which is an enlarged side view of the vicinity ofthe power unit 30, and FIG. 3, which is a perspective view from a skewupper side taken along arrow III of FIG. 2 to show the vicinity of thepower unit 30.

A throttle body 41 connected to an intake port through an intake pipe 40and an air cleaner (not shown) connected to the throttle body 41 througha connecting tube 42 are provided at a rear portion of the cylindersection 33 of the internal combustion engine 31 in the power unit 30. Afuel injection system 45 (see FIG. 3) for injecting fuel is mounted onthe throttle body 41.

An exhaust pipe 43 extending from an exhaust port is provided at a frontportion of the cylinder section 33, extends rearward, and is connectedto a muffler 44 provided at a rear portion. A spark plug 46 (FIG. 3) isprovided at a right side surface of the cylinder section 33.

A fuel tank 50 is mounted to the main frame 4 in a straddling mannerover the power unit 30. A fuel pump unit 51 is provided outside the fueltank 50, and is fixed between the left and right center frames 5 a and 5b. A fuel feed pipe 52 as a fuel passage for feeding the fuel from thefuel tank 50 to the fuel pump unit 51, and a fuel breather pipe 53 forreturning surplus fuel or vapor from the fuel pump unit 51 to the fueltank 50, are connected to the fuel pump unit 51.

In addition, the fuel pump unit 51 is disposed on the rear side of thecrankcase 32, more specifically on the rear side of the output shaft 35of the power unit 30, and on the front side of the rear shock absorber21. A fuel filter device 55 is connected to the downstream side of afuel discharge pipe 54 provided as a fuel passage for the fuelpressurized by and discharged from the fuel pump unit 51. The fuelfilter device 55 is disposed on the lower side of the fuel tank 50 andon the upper side of the crankcase 32.

The fuel pump unit 51 is disposed substantially in the center of thevehicle width (see FIG. 4), is located on the vehicle inner side in thevehicle width direction relative to the swing arm 20, and is disposed atsuch a position as to overlap with the swing arm 20 as viewed along thevehicle width direction.

In addition, the fuel pump unit 51 is located at such a position so asto overlap with the left and right center frames 5 a, 5 b located on therear side of the power unit 3, as viewed in the vehicle width direction.

In this embodiment, the fuel pump unit 51 is disposed on the rear sideof the crankcase 32, more specifically on the rear side of the outputshaft 35, and on the front side of the rear shock absorber 23. Thisensures that the fuel pump unit 51 can be laid out efficiently, and,while the fuel pump unit 51 is disposed outside the fuel tank 50, thefuel filter device 55 connected to the fuel passage on the downstreamside relative to the fuel pump unit 51 can be disposed on the upper sideof the crankcase 32. Accordingly, a space saving in regard of the layoutspace for the fuel supply system is realized.

More particularly, in the case of a motorcycle using a gasoline-ethanolmix fuel, it is highly necessary to provide a fuel filter device on thedownstream side of a fuel pump unit for the purpose of removing the dustpresent in ethanol. In that case, also, the above-mentioned space savingmakes it possible to dispose the fuel pump unit outside a fuel tank,whereby the degree of freedom in design is enhanced.

In addition, the fuel pump unit 51 is likely to be protected by theswing arm 20, and the fuel pump unit 51 is likely to be protected by thevehicle body, such as the left and right center frames 5 a, 5 b.

As shown in FIG. 2, the fuel pump unit 51 is cylindrical in shape, andis disposed adjacently to the rear shock absorber 23, which is alsocylindrical in shape. The cylinder axis Y of the fuel pump unit 51 andthe cylinder axis S of the rear shock absorber 23 are verticallyoriented substantially in parallel to each other. Consequently, thespace on the front side of the rear cushion 23 is utilized effectively,and the fuel pump unit 51 is disposed in a compact form.

The internal combustion engine 31 has its crankshaft 34 oriented in thevehicle width direction, and the center axis X of the cylinder section33 thereof is slightly slanted toward the forward side from thevertical. The cylinder axis Z of the fuel filter device 55 cylindricalin shape and the cylinder axis Y of the fuel pump unit 51 are orientedsubstantially in parallel to the cylinder axis X.

Since the cylinder section 33 and the fuel filter device 55 and the fuelpump unit 51 are disposed in this manner, in this embodiment, it ispossible to lay out the power unit 30, the fuel filter device 55 and thefuel pump unit 51 in a compact form without leaving a dead space.

FIG. 4 is a perspective view, from a skew lower side, of a rear portionof the power unit 30 and the fuel pump unit 51, taken along arrow IV ofFIG. 2. As shown in the FIG. 4, the fuel pump unit 51 is supported by afuel pump mounting stay 27, which has an annular part 27 a surroundingthe fuel pump unit 51 and left and right arm parts 27 b, 27 c extendingin the vehicle front-rear direction from the annular part 27 a. Theright arm part 27 c is supported by a support member 28 provided on theside of the center frame 5, as shown in FIG. 4.

In addition, since the fuel filter device 55 is disposed on the upperside of the crankcase 32 as above-mentioned, a lower portion of the fuelfilter device 55 is supported by the rear bracket 26 for supporting arear portion of the crankcase 32, as shown in FIG. 2.

Since the fuel pump unit 51 is disposed below the fuel filter device 55,in a structure in which the left arm part 27 b is attached to the rearbracket 26 as shown in FIG. 2, the left arm part 27 b is supported bythe crankcase 32 through the rear bracket 26.

The rear bracket 26 is supported by a rear bracket support member 29provided on the side of the center frame 5.

In this embodiment as above-described, the fuel pump unit 51 is likelyto be protected by the annular part 27 a of the fuel pump mounting stay27, and the fuel pump unit 51 is securely supported in a space-savingmanner. In addition, the fuel pump mounting stay 27 for supporting thefuel pump unit 51 is made smaller in size, and the fuel pump unit 51 canbe supported in a space-saving manner.

The fuel supply system in this embodiment includes: the fuel tank 50shown in FIGS. 1 and 2; the fuel pump unit 51 connected to the fuel tank50 through the fuel feed pipe 52 and the fuel breather pipe 53; the fuelfilter device 55; a pressure regulator 58 shown in FIG. 3; and the fuelpipes constituting a fuel passage for connecting these components to oneanother. By the fuel supply system, the fuel is supplied to a fuelinjection system 45 (FIG. 3) mounted on the throttle body 41.

The fuel pump unit 51 is connected through a fuel discharge pipe 54 toan inlet part 55 a at a lower end portion of the fuel filter device 55,and a pressurized fuel is fed into the fuel filter device 55, wherebydust present in the fuel is removed.

The fuel filter device 55 has a cylindrical body part thereof (notshown) accommodated in an outer case 56, and has its cylinder axis Zoriented in a vertical direction. The outer case 56 is composed of asupport part side case 56 a and a cover part 56 b, as will be describedlater.

An outlet part 55 b at an upper portion of the fuel filter device 55 isconnected through a fuel pipe 57 to an inlet part 53 a (not shown inFIG. 3) (see FIGS. 6 and 7) at a vertically central portion of thepressure regulator 58, the pressurized fuel cleared of dust is fed intothe pressure regulator 58, and the pressure of the fuel to be suppliedto the fuel injection system 45 is regulated.

The pressure regulator 58 is located directly under the fuel tank 50(see FIG. 6). As shown in FIG. 3, the pressure regulator 58 is disposedbetween the throttle body 41 and the fuel filter device 55 while beinglocated on the upper side of a rear portion of the crankcase 32 andoverlapping with the throttle body 41 when viewed in the vehicle widthdirection.

As shown in FIGS. 6 and 7, the pressure regulator 58 is fixed onto theouter case 56 in the state of being seated on a base part 56 c (see FIG.9) provided at an outside portion (on the inner side in the vehiclewidth direction) of the support part side case 56 a of the outer ease 56of the fuel filter device 55, with the cylinder axis R of thecylindrical body part 58 b thereof oriented in a vertical direction. Inthis instance, a side surface of the pressure regulator 58 on the sideopposite to the outer case 56 is covered with a cover member 58 dattached to the outer case 56. The pressure regulator 58 shown in FIG. 3is shown in the condition where the body part 58 b thereof is coveredwith the cover member 58 d, with the body part 58 b itself is omittedfrom the drawing. FIGS. 6 and 7 show the pressure regulator 58 in thecondition where the body part 58 b is not covered with the cover member58 d.

In addition, the pressure regulator 58 is mounted to an outside portionof the fuel filter device 55 so that its cylinder axis R is inclined atan angle α (a small angle of not more than 45°) against the cylinderaxis Z of the fuel filter device 55 in a plane along the vehicle widthdirection. Namely, the cylinder axes Z and R are not in parallel witheach other but are intersecting with each other at an angle α (see FIG.6), as viewed in the front-rear direction of the vehicle.

A surplus portion of fuel upon the pressure regulation is returned froma top portion of the pressure regulator 58 into the fuel tank 50 througha fuel return pipe 59. An outlet pipe 58 c provided at a lower portionof the pressure regulator 58 is connected to the fuel injection system45 through the fuel pipe 60, and the fuel regulated in pressure issupplied to the fuel injection system 45.

As shown in FIGS. 5 to 7, the fuel pipe 60 is laid out so as to windaround the outer case 56 of the fuel filter device 55.

In the fuel supply system according to this embodiment as describedabove, the pressure regulator 58 is not incorporated in the fuel filterdevice 55, so that the outlet pipe 58 c of the pressure regulator 58 canbe laid out in an optimum position in relation to the layout of the fuelpipe 60 for the fuel having been regulated in pressure. In addition,since the cylinder axis R of the pressure regulator 58 is inclinedagainst the cylinder axis Z of the fuel filter device 55, thewinding-around of the fuel pipe 60 is facilitated, and optimization ofthe length of the fuel pipe 60 is facilitated. Moreover, with thepressure regulator 58 mounted to an outside portion of the fuel filterdevice 55, the pressure regulator 58 is arranged in a space-savingmanner while being disposed outside the fuel filter device 55.

More particularly, in the case of a motorcycle using a gasoline-ethanolmix fuel, the length of the fuel pipe between a fuel filter device and afuel injection system must be optimized so as to secure a buffercapacity for permitting a fuel injection control device to appropriatelyrecognize a change in the composition of the fuel supplied to the fuelinjection system upon a change made in the ethanol concentrationaccording to the operating conditions. In this connection, according tothis embodiment of the present invention, the length of the fuel pipe 60between the pressure regulator 58 and the fuel injection system 45 isoptimized, whereby an effective buffer effect is produced. The spacesaving ensures that the fuel pump unit can also be disposed outside thefuel tank 50, in addition to the fuel filter device 55 which is highlyneeded to be installed outside the fuel tank 50 for enhancingmaintainability, in the case of the fuel mix.

On the other hand, with the pressure regulator 58 disposed between thefuel filter device 55 and the throttle body 41 so as to be hidden whenexternally viewed along the vehicle width direction, the pressureregulator 58 is likely to be protected, and appearance of the motorcycle1 is improved.

The pressure regulator 58 can be supported outside the fuel filterdevice 55 by a simple structure composed of the base part 56 c of theouter case 56 of the fuel filter device 55 and the cover member 58 dcovering the base part 56 c. Thus, the pressure regulator 58 can beprotected.

The pressure regulator 58 is disposed directly under the fuel tank 50,with its cylinder axis R oriented along a vertical direction, with thefuel return pipe 59 disposed on the upper side, and with the outlet pipe58 c disposed on the lower side. As a result, the fuel return pipe 59between the pressure regulator 58 and the fuel tank 50 and the fuel pipe60 between the pressure regulator 58 and the fuel injection system 45are laid out in a space-saving manner, and the length of the fuel pipe60 is secured.

The layout and configuration of apparatuses in the fuel supply systemaccording to this embodiment will be described more in detail below,based on FIG. 5, which is an apparatus layout illustration taken alongarrow V of FIG. 3 to show a left side view of the vicinity of the powerunit 30, FIG. 6, which is an apparatus layout illustration taken alongarrow VI of FIG. 5, FIG. 7, which is an apparatus layout illustrationtaken along arrow VII of FIG. 5, and FIG. 8, which is a perspective viewof the fuel filter device 55, taken along arrow VIII of FIG. 7.

As shown in FIG. 2, the fuel filter device 55 is disposed at a positionsomewhat deviated to the left side from the center of the vehicle width,in the state of overlapping with the throttle body 41 as viewed in thevehicle width direction.

Further, as shown in FIGS. 5 to 7, an upper portion of the outer case 56of the fuel filter device 55 is supported through an auxiliary bracket63 to an engine hanger boss 24 provided for fixing the power unit 30 tothe body frame 2 (reinforcing frame 9).

The auxiliary bracket 63 fixed to the engine hanger boss 24 extendsdownward, and the upper portion of the outer case 56 is fastened to theauxiliary bracket 63 by an upper portion support bolt 64.

A lower portion of the outer case 56 is fastened by a lower portionsupport bolt 65 to the rear bracket 26 provided for fixing a rearportion of the crankcase 32 to the center frame 5, and is therebysupported on the crankcase 32. The rear bracket 26 is fixed to thecenter frame 5 through the rear bracket support member 29 (FIG. 2).

More specifically, the outer case 56 is composed of the support partside case 56 a on the inner side in the vehicle width direction and thecover part 56 b on the outer side in the vehicle width direction whichcovers the support part side case 56 a, in a mounted condition. With theupper and lower portions on the support part side case 56 a side of theouter case 56 fastened in the above-mentioned manner, the support partside case 56 a is supported by the engine hanger boss 24 and thecrankcase 32.

In addition, as shown in FIG. 8, the cover part 56 b is provided withclaw portions 66 on one end side thereof. After the claw portions 66 areinserted into engaging holes 67 provided on one end side of the supportpart side case 56 a accommodating a fuel filter body part (not shown),the other end side of the cover part 56 b is fastened to the other endside of the support part side case 56 a by a fastening bolt 68, wherebythe cover part 56 b is fixed to the support part side case 56 a, and thefuel filter body part (not shown) is also fixed in the outer case 56.

As shown in FIG. 9, the support part side case 56 a is provided with theabove-mentioned base part 56 c at an outside portion (on the inner sidein the vehicle width direction) thereof. The base part 56 c is formedslantly so that the body part 58 b of the pressure regulator 58 isseated with its cylinder axis R inclined at the angle α against thecylinder axis Z of the fuel filter device 55, as shown in FIG. 6.

According to this embodiment as above, the fuel filter device 55 isdisposed in a space at a lateral side of the throttle body 41 in aspace-saving manner, and the upper and lower portions of the outer case56 thereof are supported, so that the fuel filter device 55 is firmlysupported.

More particularly, since the support part side case 56 a on the innerside in the vehicle width direction is supported by the engine hangerboss 24 and the crankcase 32, the fuel filter device 55 is firmlysupported. In addition, the cover part 56 b is fixed to the support partside case 56 a by the claw portions 66 and the fastening bolt 68 on theouter side in the vehicle width direction. Accordingly, the cover part56 b is easy to mount and dismount, so that maintenance and replacementworks for a fuel filter element in the fuel filter body part, etc. arefacilitated.

This is particularly effective in the case of a fuel supply system in amotorcycle using a gasoline-ethanol mix fuel where enhancement ofmaintainability of a fuel filter device 55 is highly in demand.

In this embodiment, the fuel pipe 60 connectingly extending from theoutlet pipe 58 c of the pressure regulator 58 to the fuel injectionsystem 45 is provided so as to wind around the outer case 56 of the fuelfilter device 55.

Therefore, while the pipe length of the fuel pipe 60 from the outletpipe 58 c of the pressure regulator 58 to the fuel injection system 45is secured and optimization of the pipe length is contrived, the fuelpipe 60 can be laid along the fuel filter device 58, whereby the fuelpipe 60 can be arranged in a space-saving manner.

In addition, the fuel pipe 60 set winding around the outer case 56 ofthe fuel filter device 55 is supported on the outer case 56 by a pipesupport part 56 d provided at the support part side case 56 a of theouter case 56, and is located so as to be adjacent to a head portion ofthe fastening bolt 68 for fastening the cover part 56 b to the supportpart side case 56 a, in the bolt axis direction T.

Therefore, the fuel pipe 60 laid winding around the outer case 56 issupported by the pipe support part 56 d so as to be adjacent to the headportion of the fastening bolt 68 in the bolt axis direction T.Accordingly, even when the fastening bolt 68 is loosened, it is held bythe fuel pipe 60, so that the fastening bolt 68 is prevented fromslipping off.

As above-mentioned, it is necessary for the fuel pipe between the fuelfilter device and the fuel injection system to be optimized in length soas to have an appropriate buffer capacity, and this necessity isparticularly strong in the case of a motorcycle using a gasoline-ethanolmix fuel, for example.

In the case where there is a limit to the regulation of a fuel pipebetween a fuel filter device and a pressure regulator, for example, inthe case where the pressure regulator 58 is mounted at an outsideportion of the fuel filter device 55 as in this embodiment, since thereis a limitation as to the length of the fuel pipe 57 between the fuelfilter device 55 and the pressure regulator 58, it is effective tooptimize the length (partial length) of the fuel pipe 60 between thepressure regulator 58 and the fuel injection system 45, instead ofoptimizing the whole length of the fuel pipe connectingly extending fromthe fuel filter device 55 to the fuel injection system 45.

The fuel tank 50 in this embodiment is mounted, in a straddling manner,on the main frame 4 (body frame 2) oriented in the front-rear directionof the vehicle.

As shown in FIGS. 10( a) and 10(b), the fuel tank 50 is provided withthree joints, namely, a feed joint 70, a breather joint 71, and a returnjoint 72.

As shown in FIGS. 11( a) and 11(b) (see FIG. 2), the feed joint 70 isconnected to the fuel pump unit 51 (see FIG. 2) through the fuel feedpipe 52, and the fuel fed from the fuel tank 50 to the fuel pump unit 51passes therethrough. The breather joint 71 is connected to the fuel pumpunit 51 through the fuel breather pipe 53, and the fuel returned fromthe fuel pump unit 51 to the fuel tank 50 passes therethrough. Thereturn joint 72 is connected through the fuel return pipe 59 to thepressure regulator 58 (see FIG. 6) provided on the downstream side ofthe fuel pump unit 51, and the fuel that is returned from the pressureregulator 58 to the fuel tank 50 passes therethrough.

In addition, as shown in FIGS. 10( a), 10(b), 11(a) and 11(b), the threejoints are fixed to the fuel tank 50 by letting them penetrate a singlereinforcing plate 73, and are arranged concentratedly at a lowermostpart of a bottom portion 74 of the fuel tank 50.

In the fuel supply system according to this embodiment asabove-described, the three joints, namely, the feed joint 70, thebreather joint 71 and the return joint 72 provided at the fuel tank 50are reinforced by the single reinforcing plate 73, so that the number ofcomponent parts is reduced, and fixation of the three joints to the fueltank 50 is facilitated. In addition, in the motorcycle 1 having the fuelpump unit 51 and the fuel filter device 55 provided outside the fueltank 50, the rigidity of pipe portions outside the fuel tank is secured,and a compact pipe layout is permitted, so that space saving as to thefuel supply system can be contrived.

More particularly, in a fuel supply system for a motorcycle using agasoline-ethanol mix fuel wherein the arrangement of a fuel filterdevice 55 outside a fuel tank 50 is highly needed for facilitatingmaintenance of the fuel filter device 55, the above-described spacesaving enables not only the fuel filter device 55 but also the fuel pumpunit 51 to be arranged outside the fuel tank, leading to an enhanceddegree of freedom in design.

In addition, the plurality of joints 70, 71, 72 can be reinforced by thesmall reinforcing plate 73. Thus, the dead residue of fuel in the fueltank 50 can be reduced.

The fuel tank 50 in this embodiment is comprises of an upper plate part75 forming an upper surface in a shape resembling an inverted bowl and abottom plate part 76 closing the lower side of the upper plate part 75and forming the bottom portion 74. The upper and lower plate parts 75and 76 are welded to each other at their lower edges 77 in aliquid-tight manner. The bottom plate part 76 is provided, at the middlein the vehicle width direction, with a recessed part 78 extending in thefront-rear direction of the vehicle and recessed upward in a tunnel-likeshape, for permitting the main frame 4 oriented in the vehiclefront-rear direction to pass therethrough. The bottom plate part 76extends downward on both lateral sides of the recessed part 78, to formside bottom parts 79. Thus, the fuel tank 50 as a whole is invertedU-shaped in section in the vehicle width direction.

As shown in FIG. 10( b), the recessed part 78 is so formed that itswidth decreases toward the rear side of the vehicle; therefore, at thebottom portion 74 a on the vehicle rear side, at least one of the leftand right side bottom parts 79 is formed to be flat in a required width.As shown in FIG. 10( a), at a position where the side bottom part 79overlaps with the main frame 4 (body frame 2) as viewed in the vehiclewidth direction, the three joints consisting of the feed joint 70, thebreather joint 71 and the return joint 72 are concentrated to the sidebottom part 79 and are fixed to the fuel tank 50 by the singlereinforcing plate 73.

The upper plate part 75 of the fuel tank 50 is provided with a fuelfiller port 81 at an upper portion thereof. A ridge 82 formed inside thefuel tank 50 by the recessed part 78 of the bottom plate part 76 isprovided with a support member 83 for a fuel level sensor (not shown),nearly at the middle in the front-rear direction of the vehicle.

Therefore, in this embodiment, while forming the bottom portion 74 ofthe fuel tank 50 in a compact form, the space for fixing the reinforcingplate 73 can be secured at the bottom portion 74 of the fuel tank 50.Thus, a space saving as to the fuel supply system can be achieved.

In addition, as shown in FIG. 10( b), the reinforcing plate 73 is formedso as to extend along the shape of the side bottom part 79, resulting inthat positioning of the reinforcing plate 73 is facilitated. Thus,mutual distances of the joints 70, 71 and 72 can be secured. Since thethree joints 70, 71 and 72 are arranged in a row along the front-reardirection of the vehicle, the side bottom parts 79 of the fuel tank 50can be made narrower, and the bottom portion 74 as a whole can be madesmaller in width.

In addition, as shown in FIG. 10( a), of the three joints 70, 71 and 72,the return joint 72 is arranged so as to open into the fuel tank 50 at ahigher position as compared with the other joints 70 and 71. Thisensures that a terminal opening part 72 a (see FIG. 11( a)) of thereturn joint 72 for the fuel returned from the pressure regulator 58 canbe set at an uppermost portion of the three joints. Thus, a preventiveeffect on the flowing-in of dust present in the fuel tank 50 into thepressure regulator 58 can be enhanced.

This is particularly effective in the case of the above-mentionedgasoline-ethanol mix fuel.

As shown in detail in FIGS. 11( a) and 11(b), the reinforcing plate 73in this embodiment is provided at its periphery with a reinforcing rib73 a, and is fixed to the inner surface side of the fuel tank 50 bybrazing or the like, with the reinforcing rib 73 a directed to theinside of the fuel tank 50. For mounting the reinforcing plate 73, thebottom plate part 76 forming the bottom portion 74 of the fuel tank 50is provided with a protuberant portion 84 for positioning thereinforcing plate 73 on the inside surface of the bottom portion 74.

The reinforcing plate 73 is mounted and fixed, using the protuberantportion 84 as a guide. At the time of press forming the protuberantportion 84, a dent 85 is formed in the outside surface of the bottomportion 74. A clip 87 for fixing a wiring 86 from the fuel level sensor(not shown) or a piping is provided at the position of the dent 85.

Therefore, the presence of the dent 85 formed in the outside surface ofthe bottom portion 74 of the fuel tank 50 can provide two functions,namely, a function of positioning the reinforcing plate 73 on the insidesurface of the bottom portion 74 of the fuel tank 50 and a function offixing the wiring 86 or piping by the clip 87 on the outside surface ofthe bottom portion 74 of the fuel tank 50.

In addition, for the purpose of reducing the dead residue of fuel in thefuel tank 50, the uppermost portion of the feed joint 70 is set to belower than the reinforcing rib 73 a.

While the fuel supply system for the motorcycle 1 according to anembodiment of the present invention has been described above, theinvention is not limited to the fuel supply system for the motorcycle 1as described in the embodiment above. As a fuel supply system, theinvention is applicable to, and can be carried out effectively in,various forms of motorcycles including a power unit having a crankcaseof an internal combustion engine, a throttle body mounted to the powerunit, a fuel injection system mounted on the throttle body, a fuel tank,a fuel pump unit by which a fuel in the fuel tank is supplied to thefuel injection system, and a fuel filter device.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A fuel supply system for a motorcycle comprising: a power unit havinga crankcase of an internal combustion engine; a throttle body mounted tothe power unit; a fuel injection system mounted on the throttle body; afuel tank; a fuel pump unit by which a fuel in the fuel tank is suppliedto the fuel injection system; a fuel filter device; wherein the fuelfilter device is disposed so as to overlap with the throttle body asviewed in a vehicle width direction; and an upper portion of an outercase of the fuel filter device is supported by an engine hanger boss forfixing the power unit to a body frame of the motorcycle, whereas a lowerportion of the outer case is supported by the crankcase.
 2. The fuelsupply system for the motorcycle according to claim 1, wherein the outercase includes a support part side case provided on an inner side in thevehicle width direction in a mounted state, and a cover part provided onan outer side in the vehicle width direction and covering the supportpart side case; the support part side ease is supported by the enginehanger boss and the crankcase; and the cover part is fixed to thesupport part side case in the condition in which a claw portion providedon one end side of the cover part is inserted into the support part sidecase and the other end side of the cover part is fastened to the supportpart side case by a fastening bolt.
 3. The fuel supply system for themotorcycle according to claim 2, wherein a part of a fuel pipeconnectingly extending from the fuel filter device to the fuel injectionsystem is set winding around the outer case of the fuel filter deviceand is supported on the outer case, by a pipe support part provided atthe outer case, in such a manner as to be adjacent to a head portion ofthe fastening volt in a bolt axis direction.
 4. The fuel supply systemfor the motorcycle according to claim 1, wherein the fuel pump unit islocated at a position below the fuel filter device, and the fuel pumpunit is supported by a fuel pump mounting stay mounted to a bracket forsupporting a lower portion of the fuel filter device.
 5. The fuel supplysystem for the motorcycle according to claim 2, wherein the fuel pumpunit is located at a position below the fuel filter device, and the fuelpump unit is supported by a fuel pump mounting stay mounted to a bracketfor supporting a lower portion of the fuel filter device.
 6. The fuelsupply system for the motorcycle according to claim 3, wherein the fuelpump unit is located at a position below the fuel filter device, and thefuel pump unit is supported by a fuel pump mounting stay mounted to abracket for supporting a lower portion of the fuel filter device.
 7. Thefuel supply system for the motorcycle according to claim 1, wherein theinternal combustion engine has a crankshaft oriented in the vehiclewidth direction, the fuel filter device and the fuel pump unit arecylindrical in shape, and disposed so that their cylinder axes areoriented substantially in parallel to a cylinder axis of the internalcombustion engine as viewed in the vehicle width direction.
 8. The fuelsupply system for the motorcycle according to claim 2, wherein theinternal combustion engine has a crankshaft oriented in the vehiclewidth direction, the fuel filter device and the fuel pump unit arecylindrical in shape, and disposed so that their cylinder axes areoriented substantially in parallel to a cylinder axis of the internalcombustion engine as viewed in the vehicle width direction.
 9. The fuelsupply system for the motorcycle according to claim 3, wherein theinternal combustion engine has a crankshaft oriented in the vehiclewidth direction, the fuel filter device and the fuel pump unit arecylindrical in shape, and disposed so that their cylinder axes areoriented substantially in parallel to a cylinder axis of the internalcombustion engine as viewed in the vehicle width direction.
 10. The fuelsupply system for the motorcycle according to claim 4, wherein theinternal combustion engine has a crankshaft oriented in the vehiclewidth direction, the fuel filter device and the fuel pump unit arecylindrical in shape, and disposed so that their cylinder axes areoriented substantially in parallel to a cylinder axis of the internalcombustion engine as viewed in the vehicle width direction.
 11. The fuelsupply system for the motorcycle according to claim 1, wherein themotorcycle has a rear shock absorber provided in a vertically orientedstate, and the fuel pump unit is disposed on the rear side of thecrankcase and on the front side of the rear shock absorber.
 12. The fuelsupply system for the motorcycle according to claim 2, wherein themotorcycle has a rear shock absorber provided in a vertically orientedstate, and the fuel pump unit is disposed on the rear side of thecrankcase and on the front side of the rear shock absorber.
 13. The fuelsupply system for the motorcycle according to claim 3, wherein themotorcycle has a rear shock absorber provided in a vertically orientedstate, and the fuel pump unit is disposed on the rear side of thecrankcase and on the front side of the rear shock absorber.
 14. The fuelsupply system for the motorcycle according to claim 4, wherein themotorcycle has a rear shock absorber provided in a vertically orientedstate, and the fuel pump unit is disposed on the rear side of thecrankcase and on the front side of the rear shock absorber.
 15. The fuelsupply system for the motorcycle according to claim 7, wherein themotorcycle has a rear shock absorber provided in a vertically orientedstate, and the fuel pump unit is disposed on the rear side of thecrankcase and on the front side of the rear shock absorber.
 16. The fuelsupply system for the motorcycle according to claim 11, wherein themotorcycle has a swing arm supported by the rear shock absorber androtatably supporting a rear wheel, and the fuel pump unit is disposed ata position on a vehicle inner side in the vehicle width directionrelative to the swing arm, the position being such that the fuel pumpunit overlaps with the swing arm when viewed in the vehicle widthdirection.
 17. The fuel supply system for the motorcycle according toclaim 11, wherein the fuel pump unit is cylindrical in shape, and isdisposed adjacent to the rear shock absorber, with its cylinder axisoriented in a vertical direction substantially parallel to the rearshock absorber.
 18. The fuel supply system for the motorcycle accordingto claim 16, wherein the fuel pump unit is cylindrical in shape, and isdisposed adjacent to the rear shock absorber, with its cylinder axisoriented in a vertical direction substantially parallel to the rearshock absorber.
 19. A fuel supply system adapted for use with amotorcycle comprising: a fuel injection system mounted on the throttlebody; a fuel tank; a fuel pump unit for supplying fuel to the fuelinjection system; a fuel filter device; and an upper portion of an outercase of the fuel filter device is supported by an engine hanger boss forfixing the power unit to a body frame of the motorcycle, whereas a lowerportion of the outer case is supported by the crankcase.
 20. The fuelsupply system adapted for use with the motorcycle according to claim 19,wherein the outer case includes a support part side case provided on aninner side in the vehicle width direction in a mounted state, and acover part provided on an outer side in the vehicle width direction andcovering the support part side case; the support part side case issupported by the engine hanger boss and the crankcase; and the coverpart is fixed to the support part side case in the condition in which aclaw portion provided on one end side of the cover part is inserted intothe support part side case and the other end side of the cover part isfastened to the support part side case by a fastening bolt.